Whole-brain CT perfusion on admission predicts delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Risk Factors and Clinical Significance of Ultra-Long-Term Microischemia After Intracranial Aneurysm Embolization

INTRODUCTION

This study aimed to explore influencing factors and clinical significance of ultra-long-term microischemia following intracranial aneurysm (IA) embolization and establish a theoretical foundation for reducing both the incidence of ultra-long-term microischemia and cognitive dysfunction in patients post embolization.

METHODS

A retrospective analysis was conducted on data from 147 patients who received endovascular treatment for IAs. Patients were categorized into microischemic and control (non-microischemic) groups on the based on the findings of high-resolution magnetic resonance vessel wall imaging (HR-VWI) examinations performed 3 days postoperatively and 6 months postoperatively. Risk factors for the occurrence of ultra-long-term microischemia were determined by univariate analysis and multivariate logistic regression analysis.

RESULTS

Out of 147 patients included in the study, 51 (34.69%) developed microischemia while the remaining 96 (65.31%) did not experience this condition. Analysis revealed that factors such as sex, age, history of underlying diseases (hypertension, diabetes mellitus), aneurysmal site characteristics, the presence or absence of stenosis in the aneurysm-bearing artery, modified Fisher score at admission, Barthel's index at discharge, immunoinflammatory index at 3 days postoperatively and at the 6-month follow-up, the presence or absence of aneurysmal wall enhancement, and the presence or absence of aneurysmal lumen showed no statistically significant differences between the two groups (all P > 0.05). By contrast, variables like in operative time, rupture status of the aneurysm before surgery according to World Federation of Neurologic Surgeons (WFNS) grade, aneurysm size, number of stents used, number of guidewires and catheters used, and Evans index between the two groups were found to have statistically significant disparities between those who developed microischemia and those who did not (P < 0.05). A subsequent multivariate analysis revealed that aneurysm size, Evans index, and the number of stents used were independent risk factors for the occurrence of ultra-long-term microischemia after surgical intervention of aneurysms (P < 0.05). The receiver operating characteristic (ROC) curves of the patients were constructed on the basis of risk factors determined through multivariate logistic regression analysis. Results indicated that aneurysm size (area under ROC curve (AUC) 0.619, sensitivity 94.7%, specificity 17.1%, P = 0.049), Evans index (AUC 0.670, sensitivity 96.4%, specificity 26.8%, P = 0.004), and number of stents (AUC 0.639, sensitivity 44.6%, specificity 90.2%, P < 0.001) effectively predicted the occurrence of microischemia. The incidence of cognitive dysfunction was higher in the microischemic group than in the control group (P < 0.05), and a greater number of microischemic foci was associated with a higher incidence of cognitive dysfunction. The proportion of microschemia foci in the thalamus and basal ganglia in patients with cognitive dysfunction (60.87%) was significantly higher than that in patients without cognitive dysfunction (34.55%) (P < 0.05).

CONCLUSION

Aneurysm size, Evans index > 0.3, and the quantity of stents were independent risk factors for the occurrence of ultra-long-term microischemia after aneurysm embolization and provided good predictive performance. Cognitive dysfunction was closely associated with microischemia, with its severity increasing with an increase in the number of ischemic foci.

CTP for the Screening of Vasospasm and Delayed Cerebral Ischemia in Aneurysmal SAH: A Systematic Review and Meta-analysis

BACKGROUND

Delayed cerebral ischemia and vasospasm are the most common causes of late morbidity following aneurysmal SAH, but their diagnosis remains challenging.

PURPOSE

This systematic review and meta-analysis investigated the diagnostic performance of CTP for detection of delayed cerebral ischemia and vasospasm in the setting of aneurysmal SAH.

DATA SOURCES

Studies evaluating the diagnostic performance of CTP in the setting of aneurysmal SAH were searched on the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Cochrane Clinical Answers, Cochrane Methodology Register, Ovid MEDLINE, EMBASE, American College of Physicians Journal Club, Database of Abstracts of Reviews of Effects, Health Technology Assessment, National Health Service Economic Evaluation Database, PubMed, and Google Scholar from their inception to September 2023.

STUDY SELECTION

Thirty studies were included, encompassing 1786 patients with aneurysmal SAH and 2302 CTP studies. Studies were included if they compared the diagnostic accuracy of CTP with a reference standard (clinical or radiologic delayed cerebral ischemia, angiographic spasm) for the detection of delayed cerebral ischemia or vasospasm in patients with aneurysmal SAH. The primary outcome was accuracy for the detection of delayed cerebral ischemia or vasospasm.

DATA ANALYSIS

Bivariate random effects models were used to pool outcomes for sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio. Subgroup analyses for individual CTP parameters and early-versus-late study timing were performed. Bias and applicability were assessed using the modified QUADAS-2 tool.

DATA SYNTHESIS

For assessment of delayed cerebral ischemia, CTP demonstrated a pooled sensitivity of 82.1% (95% CI, 74.5%-87.8%), specificity of 79.6% (95% CI, 73.0%-84.9%), positive likelihood ratio of 4.01 (95% CI, 2.94-5.47), and negative likelihood ratio of 0.23 (95% CI, 0.12-0.33). For assessment of vasospasm, CTP showed a pooled sensitivity of 85.6% (95% CI, 74.2%-92.5%), specificity of 87.9% (95% CI, 79.2%-93.3%), positive likelihood ratio of 7.10 (95% CI, 3.87-13.04), and negative likelihood ratio of 0.16 (95% CI, 0.09-0.31).

LIMITATIONS

QUADAS-2 assessment identified 12 articles with low risk, 11 with moderate risk, and 7 with a high risk of bias.

CONCLUSIONS

For delayed cerebral ischemia, CTP had a sensitivity of >80%, specificity of >75%, and a low negative likelihood ratio of 0.23. CTP had better performance for the detection of vasospasm, with sensitivity and specificity of >85% and a low negative likelihood ratio of 0.16. Although the accuracy offers the potential for CTP to be used in limited clinical contexts, standardization of CTP techniques and high-quality randomized trials evaluating its impact are required.

Intraparenchymal near-infrared spectroscopy for detection of delayed cerebral ischemia in poor-grade aneurysmal subarachnoid hemorrhage

OBJECTIVE

Detection of delayed cerebral ischemia (DCI) is challenging in comatose patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH). Brain tissue oxygen pressure (PbtO2) monitoring may allow early detection of its occurrence. Recently, a probe for combined measurement of intracranial pressure (ICP) and intraparenchymal near-infrared spectroscopy (NIRS) has become available. In this pilot study, the parameters PbtO2, Hboxy, Hbdeoxy, Hbtotal and rSO2 were measured in parallel and evaluated for their potential to detect perfusion deficits or cerebral infarction.

METHODS

In patients undergoing multimodal neuromonitoring due to poor neurological condition after aSAH, Clark oxygen probes, microdialysis and NIRS-ICP probes were applied. DCI was suspected when the measured parameters in neuromonitoring deteriorated. Thus, perfusion CT scan was performed as follow up, and DCI was confirmed as perfusion deficit. Median values for PbtO2, Hboxy, Hbdeoxy, Hbtotal and rSO2 in patients with perfusion deficit (Tmax > 6 s in at least 1 vascular territory) and/or already demarked infarcts were compared in 24- and 48-hour time frames before imaging.

RESULTS

Data from 19 patients (14 University Hospital Zurich, 5 Charité Universitätsmedizin Berlin) were prospectively collected and analyzed. In patients with perfusion deficits, the median values for Hbtotal and Hboxy in both time frames were significantly lower. With perfusion deficits, the median values for Hboxy and Hbtotal in the 24 h time frame were 46,3 [39.6, 51.8] µmol/l (no perfusion deficits 53 [45.9, 55.4] µmol/l, p = 0.019) and 69,3 [61.9, 73.6] µmol/l (no perfusion deficits 74,6 [70.1, 79.6] µmol/l, p = 0.010), in the 48 h time frame 45,9 [39.4, 51.5] µmol/l (no perfusion deficits 52,9 [48.1, 55.1] µmol/l, p = 0.011) and 69,5 [62.4, 74.3] µmol/l (no perfusion deficits 75 [70,80] µmol/l, p = 0.008), respectively. In patients with perfusion deficits, PbtO2 showed no differences in both time frames. PbtO2 was significantly lower in patients with infarctions in both time frames. The median PbtO2 was 17,3 [8,25] mmHg (with no infarctions 29 [22.5, 36] mmHg, p = 0.006) in the 24 h time frame and 21,6 [11.1, 26.4] mmHg (with no infarctions 31 [22,35] mmHg, p = 0.042) in the 48 h time frame. In patients with infarctions, the median values of parameters measured by NIRS showed no significant differences.

CONCLUSIONS

The combined NIRS-ICP probe may be useful for early detection of cerebral perfusion deficits and impending DCI. Validation in larger patient collectives is needed.

Elevated cortical blood flow insufficiency volume as a predictor of adverse outcomes in aneurysmal subarachnoid hemorrhage: a large prospective quantitative computed tomography perfusion study

PURPOSE

Early hypoperfusion changes exist in patients with aneurysmal subarachnoid hemorrhage (aSAH). We aimed to investigate a readily obtainable quantitative computed tomography perfusion (CTP) parameter that could assist in quickly identifying patients at risk of delayed cerebral ischemia (DCI) and poor 90-day functional outcomes on admission.

METHODS

We prospectively collected data between 2021.04 and 2022.12. Preoperative CTP data were post-processed using RAPID software. The cortical blood flow insufficiency (CBFI) was defined as Time-to-maximum > 4.0 s. Patients were categorized into four groups according to CBFI volume distribution. To minimize differences among the groups, we employed stabilized inverse probability of treatment weighting (sIPTW). The primary outcome was DCI and poor 90-day functional outcomes (modified Rankin Scale, 3-6) was the secondary outcome. Multivariable Cox or Logistic analysis were performed to estimate the association between CBFI volume and the study outcomes, both before and after sIPTW.

RESULTS

At baseline, the mean (SD) age of the 493 participants was 55.0 (11.8) years, and 299 (60.6%) were female. One hundred and seven participants with DCI and eighty-six participants with poor 90-day functional outcomes were identified. After sIPTW, CBFI volume demonstrated a significant association with DCI (Cox regression: Group 4 versus Group 1, HR 3.69, 95% CI 1.84-7.01) and poor 90-day functional outcomes (Logistic regression: Group 4 versus Group 1, OR 4.61, 95% CI 2.01-12.50).

CONCLUSION

In this study, an elevated preoperative CBFI volume was associated with adverse outcomes in aSAH patients. More well-designed studies are needed to confirm this association.

Whole-brain CT Perfusion at Admission and During Delayed Time-window Detects the Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

To evaluate the utility of computed tomography perfusion (CTP) both at admission and during delayed cerebral ischemia time-window (DCITW) in the detection of delayed cerebral ischemia (DCI) and the change in CTP parameters from admission to DCITW following aneurysmal subarachnoid hemorrhage.

METHODS

Eighty patients underwent CTP at admission and during DCITW. The mean and extreme values of all CTP parameters at admission and during DCITW were compared between the DCI group and non-DCI group, and comparisons were also made between admission and DCITW within each group. The qualitative color-coded perfusion maps were recorded. Finally, the relationship between CTP parameters and DCI was assessed by receiver operating characteristic (ROC) analyses.

RESULTS

With the exception of cerebral blood volume (P=0.295, admission; P=0.682, DCITW), there were significant differences in the mean quantitative CTP parameters between DCI and non-DCI patients both at admission and during DCITW. In the DCI group, the extreme parameters were significantly different between admission and DCITW. The DCI group also showed a deteriorative trend in the qualitative color-coded perfusion maps. For the detection of DCI, mean transit time to the center of the impulse response function (Tmax) at admission and mean time to start (TTS) during DCITW had the largest area under curve (AUC), 0.698 and 0.789, respectively.

CONCLUSION

Whole-brain CTP can predict the occurrence of DCI at admission and diagnose DCI during DCITW. The extreme quantitative parameters and qualitative color-coded perfusion maps can better reflect the perfusion changes of patients with DCI from admission to DCITW.

Pathophysiology of Early Brain Injury and Its Association with Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage: A Review of Current Literature

Background: Delayed cerebral ischemia (DCI) is a common and serious complication of aneurysmal subarachnoid hemorrhage (aSAH). Though many clinical trials have looked at therapies for DCI and vasospasm in aSAH, along with reducing rebleeding risks, none have led to improving outcomes in this patient population. We present an up-to-date review of the pathophysiology of DCI and its association with early brain injury (EBI). Recent Findings: Recent studies have demonstrated that EBI, as opposed to delayed brain injury, is the main contributor to downstream pathophysiological mechanisms that play a role in the development of DCI. New predictive models, including advanced monitoring and neuroimaging techniques, can help detect EBI and improve the clinical management of aSAH patients. Summary: EBI, the severity of subarachnoid hemorrhage, and physiological/imaging markers can serve as indicators for potential early therapeutics in aSAH. The microcellular milieu and hemodynamic pathomechanisms should remain a focus of researchers and clinicians. With the advancement in understanding the pathophysiology of DCI, we are hopeful that we will make strides toward better outcomes for this unique patient population.

Relationship between preoperative external ventricular drainage and preoperative rebleeding in aneurysmal subarachnoid hemorrhage: A meta-analysis

OBJECTIVE

To analyze published evidence on the relationship between preoperative external ventricular drainage (preop-EVD) and preoperative rebleeding (preop-rebleeding) in aneurysmal subarachnoid hemorrhage (aSAH).

METHOD

A comprehensive search of three databases (PubMed, Ovid EMBASE, and The Cochrane Library) was conducted from their commencement to March 31, 2022. We collected studies reporting preop-EVD of rupture aneurysms while preop-rebleeding events were documented in these studies. We also extracted information on risk factors for preop-rebleeding from the studies and used Review Manager version 5.3 software to analyze.

RESULTS

A total of 3671 cases from 14 articles were enrolled in this meta-analysis. Preop-rebleeding rate was 11.04 % (106/960) and 9.22 % (250/2711) in preop-EVD group and control group, respectively. The study lacked power to conclude a clinically significant increase in preop-rebleeding risk (OR=1.60, 95 %CI:0.82-3.22). Fisher> 2 (OR=1.86), modified Fisher> 2 (OR=7.57), World Federation of Neurological Surgeons (WFNS)> 2 (OR=4.39) and aneurysm size > 1 cm (OR=3.01) were risk factors of preop-rebleeding. Patients with Hunt-Hess (HH)> 2 showed a higher preop-rebleeding trend compared to HH≤ 2, but the result did not reach a statistical difference (OR=6.79, P = 0.06). No difference in preop-rebleeding risk between anterior circulation aneurysms and posterior circulation aneurysms. Hydrocephalus had also been shown to be unrelated to higher preop-rebleeding rate.

CONCLUSIONS

Current evidence does not support that preop-EVD significantly increases the risk of rebleeding prior to aneurysm repair. Patients with poorer clinical status on admission and aneurysms size > 1 cm are at a higher risk of preop-rebleeding.

Acute hydrocephalus and delayed cerebral infarction after aneurysmal subarachnoid hemorrhage

BACKGROUND

Delayed cerebral infarction (DCIn) following aneurysmal subarachnoid hemorrhage (aSAH) is a major cause of morbi-mortality; yet, the causes for DCIn remain incompletely understood.

OBJECTIVE

We tested the hypothesis that acute hydrocephalus could be related to the occurrence of DCIn, independently of the occurrence and severity of vasospasm.

METHODS

Radiological and clinical data of patients treated at a single large volume academic center for aSAH between 2017 and 2019 were retrospectively analyzed. DCIn was defined as imaging stigma of cerebral infarction visible on 6-week imaging follow-up after aSAH. Hydrocephalus was defined on baseline imaging as a relative bicaudate index above 1. Cerebral vasospasm was defined by reduction of artery diameter in comparison with initial diameter. We used uni- and multivariable models to test the associations between these variables, hydrocephalus and DCIn.

RESULTS

Of 164 included patients, vasospasm occurred in 58 patients (35.4%), and DCIn in 47 (28.7%). Acute hydrocephalus was present in 85 patients (51.8%) on baseline CT. No relation was found between acute hydrocephalus and delayed cerebral infarction in our multivariate analysis (adjusted OR: 1.20 95% CI [0.43-3.37]; p = 0.732). Only vasospasm occurrence was independently associated with DCIn (adjusted OR: 10.97 95% CI [4.60-26.01]).

CONCLUSION

Our study did not show an association between acute hydrocephalus and DCIn after aSAH, after adjustment for the presence and severity of cerebral vasospasm.

The value of early CT perfusion parameters for predicting delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

Delayed cerebral ischemia (DCI) is a devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). We aim to investigate the efficacy of early CT perfusion (CTP) parameters for predicting DCI in patients with aSAH. The search was conducted in five databases (PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and China Biology Medicine database). Studies were reviewed by two independent authors, and the included studies were assessed for methodological quality. Fifteen studies with 882 participants were included for the final analysis. The meta-analysis of quantitative parameters showed that mean transit time represented the most valuable predictor when the calculation of the mean value was uniformed (MD 0.30 s, 95% CI: 0.10 to 0.49 s, P = 0.003). Semi-quantitative parameters using relative values or index scores were also widely used to minimize undue variations derived from patients, operators, machines, and software. Studies also demonstrated that these relative parameters had better predictive accuracy than corresponding absolute parameters. Perfusion thresholds in each study were incomparable, and the results warranted further validation. The best threshold for the prediction was 0.9 using the relative cerebral blood flow parameter (sensitivity 97% and specificity 89%). We conclude that CTP in the early phase is a promising tool for predicting DCI in aSAH patients. However, the parameters require standardization. Future studies with prospective, multi-centered design and large sample size are needed to validate the thresholds and optimize the parameters.

Whole-Brain Permeability Analysis on Admission Improves Prediction of Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage

PURPOSE

To evaluate the changes of blood-brain barrier permeability (BBBP) after aneurysmal subarachnoid hemorrhage (aSAH) and find out whether BBBP within 24 h after onset can further improve prediction of delayed cerebral ischemia (DCI).

METHODS

CT perfusion (CTP) was performed within 24 h after onset and in the DCI time window (DCITW). Whole brain average values of flow extraction product (mK^trans), qualitative and quantitative CTP parameters, and clinical data were compared between DCI and non-DCI groups. The changes of mK^trans were analysed using a Paired t test. Multivariate logistic regression analysis and ROC analyses were performed to identify predictors of DCI and evaluate the predictive performance.

RESULTS

One hundred and forty of 179 consecutive patients were included, 45 of whom (32%) developed DCI. mK^trans was higher in the DCI group both on admission and in the DCITW (P<0.001). mK^trans decreased significantly in the non-DCI group (P=0.003), but not in DCI group (P=0.285). Multivariate logistic regression analysis showed that mK^trans (OR=1.07, 95%CI: 1.03-1.11, P<0.001), World Federation of Neurosurgery Scale (OR=6.73, 95%CI: 1.09-41.41, P=0.040), Hunt-Hess grade (OR=0.16, 95%CI: 0.02-1.19, P=0.073), modified Fisher Score (OR=3.74, 95%CI: 1.30-10.75, P=0.014), and qualitative CTP (OR=4.31, 95%CI: 1.49-12.47, P=0.007) were independent predictors of DCI. The model with K^trans produced a larger AUC of 0.88 (95%CI: 0.81-0.95), with corresponding sensitivity and specificity of 84% and 86%, respectively.

CONCLUSION

BBBP measurement within 24 h after onset can improve the prediction of DCI. Early moderate BBB disruption may be reversible, whereas severe BBBP disruption indicates the risk of DCI.

Role of microcirculatory impairment in delayed cerebral ischemia and outcome after aneurysmal subarachnoid hemorrhage

Early brain injury (EBI) is considered an important cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). As a factor in EBI, microcirculatory dysfunction has become a focus of interest, but whether microcirculatory dysfunction is more important than angiographic vasospasm (aVS) remains unclear. Using data from 128 cases, we measured the time to peak (TTP) in several regions of interest on digital subtraction angiography. The intracerebral circulation time (iCCT) was obtained between the TTP in the ultra-early phase (the baseline iCCT) and in the subacute phase and/or at delayed cerebral ischemia (DCI) onset (the follow-up iCCT). In addition, the difference in the iCCT was calculated by subtracting the baseline iCCT from the follow-up iCCT. Univariate analysis showed that DCI was significantly increased in those patients with a prolonged baseline iCCT, prolonged follow-up iCCT, increased differences in the iCCT, and with severe aVS. Poor outcome was significantly increased in patients with prolonged follow-up iCCT and increased differences in the iCCT. Multivariate analysis revealed that increased differences in the iCCT were a significant risk factor that increased DCI and poor outcome. The results suggest that the increasing microcirculatory dysfunction over time, not aVS, causes DCI and poor outcome after aneurysmal aSAH.

Impact of Implementing an Elaborated CT Perfusion Protocol for Aneurysmal SAH on Functional Outcome: CTP Protocol for SAH

BACKGROUND AND PURPOSE

The acute phase of aneurysmal SAH is characterized by a plethora of impending complications with the potential to worsen patients' outcomes. The aim of this study was to evaluate whether an elaborated CTP-based imaging protocol during the acute aneurysmal SAH phase is able to prevent delayed infarctions and contribute to a better outcome.

MATERIALS AND METHODS

In 2012, an elaborated CTP-based protocol was implemented for the management of patients with aneurysmal SAH. Retrospective analysis of patients with aneurysmal SAH treated from 2010 to 2013 was performed, comparing the patients treated before (group one, 2010-2011) with those treated after the protocol implementation (group two, 2012-2013) with regard to delayed infarctions and outcome according to the mRS at 3-months' follow-up.

RESULTS

A total of 133 patients were enrolled, of whom 57 were included in group 1, and 76, in group 2. There were no significant differences between the groups concerning baseline characteristics. In the multivariate analysis, independent predictors of a good outcome (mRS ≤ 2) were younger age (P < .001), lower World Federation of Neurosurgical Societies grade (P < .001), absence of delayed infarction (P = .01), and management according to the CTP protocol (P = .01). Larger or multiple infarctions occurred significantly more often in group 1 compared with group 2 (88% versus 33% of all delayed infarctions, P = .03). The outcome in group 2 was significantly better compared with group 1 (P = .005).

CONCLUSIONS

The findings suggest that implementation of an elaborated CTP protocol is associated with a better outcome. An earlier initiation of further diagnostics and treatment with prevention of large territorial and/or multiple infarctions might have led to this finding.

Radiation Exposure in the Acute Phase after Aneurysmal Subarachnoid Hemorrhage in the Era of CT Perfusion

PURPOSE

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with a high risk of developing multiple complications requiring further diagnostics including imaging associated with radiation exposure (RE). Since aSAH often affects younger patients, the obtained cumulative RE may have serious long-term health consequences. The aim of this study was to calculate the cumulative RE in the acute phase after aSAH and to identify contributors to RE. Additionally, we investigated whether there is a correlation of RE with outcome.

METHODS

A retrospective analysis of patients with aSAH treated at our department from 2012 to 2018 was performed. The radiation dose of every single cranial radiological examination was calculated for every patient. The outcome was assessed according to the modified Rankin scale (mRS) 3 months after ictus. Factors associated with high RE were evaluated and the correlation of RE with outcome was assessed.

RESULTS

In 268 included consecutive patients, the mean cumulative RE per patient was 39.95 mSv, ranging from 2 to 265.5 mSv. A higher RE correlated with delayed cerebral ischemia (r = 0.52, p < 0.0001), delayed infarction (r = 0.25, p < 0.0001), delayed ischemic neurological deficits (r = 0.29, p < 0.0001) and transcranial Doppler (TCD)-vasospasm (r = 0.34, p < 0.0001). Independent predictors of outcome were age (p = 0.0001), World Federation of Neurosurgical Societies (WFNS) grade (p < 0.0001) and delayed infarction (p = 0.0004), while RE did not correlate with outcome.

CONCLUSION

There is a considerable imaging-related RE in aSAH patients. A meticulous decision-making process and imaging protocols with lower RE for the deployment of CT-based and fluoroscopy-based imaging is indicated in order to minimize the risk for radiation-mediated heath consequences in this patient population.

Association Between Spreading Depolarization and Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: Post Hoc Analysis of a Randomized Trial of the Effect of Cilostazol on Delayed Cerebral Ischemia

BACKGROUND

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) remains an important problem with a complex pathophysiology. We used data from a single-center randomized trial to assess the effect of a phosphodiesterase inhibitor, cilostazol, in patients with aneurysmal SAH to explore the relationships of DCI with vasospasm, spreading depolarization (SD) and microcirculatory disturbance.

METHODS

A post hoc analysis of a single-center, prospective, randomized trial of the effect of cilostazol on DCI and SD after aneurysmal SAH was performed. From all randomized cohorts, patients who underwent both SD monitoring and digital subtraction angiography (DSA) on day 9 ± 2 from onset were included. Cerebral circulation time (CCT), which was divided into proximal CCT and peripheral CCT (as a measure of microcirculatory disturbance), was obtained from DSA. Logistic regression was conducted to determine factors associated with DCI.

RESULTS

Complete data were available for 28 of 50 patients. Of the 28 patients, 8 (28.5%) had DCI during the study period. Multivariate analysis indicated a strong association between the number of SDs on the day DSA was performed (i.e., a delayed time point after SAH onset) and DCI (odds ratio 2.064, 95% confidence interval 1.045-4.075, P = 0.037, area under the curve 0.836), whereas the degree of angiographic vasospasm and peripheral CCT were not significant factors for DCI.

CONCLUSIONS

There is a strong association between SD and DCI. Our results suggest that SD is an important therapeutic target and a potentially useful biomarker for DCI.

How to diagnose delayed cerebral ischaemia and symptomatic vasospasm and prevent cerebral infarction in patients with subarachnoid haemorrhage

PURPOSE OF REVIEW

Delayed cerebral ischaemia (DCI) complicates the clinical course of patients with subarachnoid haemorrhage (SAH) in 20--30% and substantially worsens outcome. In this review, we describe a multimodal diagnostic approach based on underlying mechanisms of DCI and provide treatment options with a special focus on the most recently published literature.

RECENT FINDINGS

Symptomatic vasospasm refers to clinical deterioration in the presence of vasospasm whereas DCI constitutes multiple causes. Pathophysiologic mechanisms underlying DCI range beyond large vessel vasospasm from neuroinflammation, to microthromboembolism, impaired cerebral autoregulation, cortical spreading depolarizations and many others. The current definition of DCI can be challenged by these mechanisms. We propose a pragmatic approach using a combination of clinical examination, cerebral ultrasonography, neuroimaging modalities and multimodal neuromonitoring to trigger therapeutic interventions in the presence of DCI. In addition to prophylactic nimodipine and management principles to improve oxygen delivery and decrease the brain metabolic demand, other specific interventions include permissive hypertension, intra-arterial application of calcium channel blockers and in selected patients angioplasty.

SUMMARY

The complex pathophysiology underlying DCI urges for a multimodal diagnostic approach triggering targeted interventions. Novel treatment concepts still have to be proven in large trials.

Optimal intracranial pressure in patients with aneurysmal subarachnoid hemorrhage treated with coiling and requiring external ventricular drainage

Optimal management of intracranial pressure (ICP) among aneurysmal subarachnoid hemorrhage (aSAH) patients requiring external ventricular drainage (EVD) is controversial. To analyze predictors of delayed cerebral ischemia (DCI)-related cerebral infarction after aSAH and the influence of ICP values on DCI, we prospectively collected consecutive patients with aSAH receiving coiling and requiring EVD. Predictors of DCI-related cerebral infarction (new CT hypodensities developed within the first 3 weeks not related to other causes) were studied. Vasospasm and brain hypoperfusion were studied with CT angiography and CT perfusion (RAPID-software). Among 50 aSAH patients requiring EVD, 21 (42%) developed DCI-related cerebral infarction, while 27 (54%) presented vasospasm. Mean ICP ranged between 2 and 19 mmHg. On the multivariate analysis, the mean ICP (OR = 2, 95%CI = 1.01-3.9, p = 0.042) and the mean hypoperfusion volume on Tmax delay > 6 (OR = 1.2, 95%CI = 1.01-1.3, p = 0.025) were independent predictors of DCI. To predict DCI-related cerebral infarction, Tmax delay > 6 s presented the highest AUC (0.956, SE = 0.025), with a cutoff value of 18 ml showing sensitivity, specificity, PPV, NPV, and accuracy of 90.5% (95%CI = 69-98.8%), 86.2% (95%CI = 68.4-96%), 82.6% (95%CI = 65.4-92%), 92.5% (95%CI = 77-98%), and 88% (95%CI = 75-95%), respectively. The AUC of the mean ICP was 0.825 (SE = 0.057), and the best cutoff value was 6.7 mmHg providing sensitivity, specificity, PPV, NPV, and accuracy of 71.4% (95%CI = 48-89%), 62% (95%CI = 42-79%), 58% (95%CI = 44-70%), 75% (95%CI = 59-86%), and 66% (95%CI = 51-79%) for the prediction of DCI-related cerebral infarction, respectively. Among aSAH patients receiving coiling and EVD, lower ICP (< 6.7 mmHg in our study) could potentially be beneficial in decreasing DCI-related cerebral infarction. Brain hypoperfusion with a volume > 18 ml at Tmax delay > 6 s presents a high sensibility and specificity in prediction of DCI-related cerebral infarction.